Drill rod and detachable bit



Dec. 11, 1934.

c. LANG I DRILL ROD AND DETACHABLE BIT Filed Aug. 11, 1931////VAV///////,.

INVENTOR K/MU'ZKS Lar BY His ATTORNEYS V/AAAAQ Patented Dec. 11, 1934PATENT OFFICE DRILL ROD AND DETACHABLE BIT Charles Lang, JerseyCity, N.J.

Application August 11,

4 Claims.

This invention pertains generally to tools, and pertains moreparticularly to tools used for drilling, cutting, etc.

Although the invention will be shown and described in connection with arock drill, it is to be understood that it may have many otherapplications. 1

Many rock drills are formed by upsetting the end of 'a drill rod andforming the bit on the upset portion. Inasmuch as the bits become dullfairly quickly, a great deal of time and labor are spent in transportingthe drill rods to and from the shop for resharpening, hardening andtempering purposes. The length and weight of each drill rod may be suchas to make this procedure very inconvenient.

Furthermore, in view of the fact that the shop for resharpening etc.must be somewhere convenient to the job on which the drills are used,it-will necessarily be of a portable nature and therefore is very likelyto be without facilities for careful control of temperatures sonecessary in obtaining the best results in steel treating.

- Moreover, a large amount of steel is tied up during the resharpeningprocess.

In view of the fact that there are more or less distinct limits in theamount of upsetting that can be done on the end of a drill rod for theformation of a bit, the sizes thereof for a particular size of drill rodare limited to a very narrow range, and it is therefore necessary tohave different sizes of drill rodsfor different sizes of bits, thusfurther increasing the amount of steel tied up in drill rods.

The solution of this problem is quite obviously that of having removablebits for the drill rods. Various forms of removable bits have beenproposed heretofore, most of which involve the use of a separate piecein addition to the drill rod and bit to connect the bit to the rod, orinvolve structures for attaching the bit to the drill rod which do notpermit a proper transmittal of the forces from the drill rod to the bit,or do not permit easy removal of the bit from the drill rod for renewalpurposes, or do not have the desired simplicity of construction topermit ease of manufacture in quantity at a relatively low cost, and topermit continued renewals of the bit without renewal of the drill rod.In many of the three piece constructions the forces from the drill rodare not properly transmitted to the bit.

Replaceable bits may be made at a fully equipped plant where steeltreating can be carefully controlled. Transportation becomes a 1931,Serial No. 556,357

small item. The bits may therefore be shipped to and from the plantwithout much inconvenience. Furthermore a sufliciently simpleconstruction will permit bringing down the original cost to a pointwhere it will be less costly to discard the bits after they become dull,thus eliminating the time and trouble of resharpening.

According to my invention the bit is attached to the drill rod in such amanner that the members which hold the bit and drill rod together do notfunction primarily, if at all, for the purpose of transmitting theforces from the drill rod to the bit. The bit may be readily and easilyremoved, and in view of the fact that the attaching parts are notsubjected to the forces of drilling, these parts have an unusually longlife. particularly if each has been given the proper heat treatment aswill be hereinafter described.

The parts for transmitting the drilling forces absorb all of thestresses of drilling, and are positioned so as to efliciently transmitthe drilling forces from the drill rod to the bit.

Although the members for holding the bit and drill rod together may alsofunction to prevent relative rotation between the bit and the drill rodduring the drilling, special means may be provided, if desired, torelieve such members from the torsional stresses.

Referring to the drawing in which like reference characters are appendedto like parts in the various figures,

Figure 1 is an elevation, partly in section, of the end of a drill rodwith a bit attached thereto.

Figure 2 is a view on line 2-2 of Figure 1.

Figure 3 is a sectional elevation of the end of a drill rod, showinganother form of the invention.

Figure 4 is a bottom plan view of the drill rod shown in Figure 3.

Figure 5 is an elevation, partly in section, showing a different form ofthe invention.

Figure 6 is an elevation, partly in section, illustrating a further formof the invention.

Figure 7 is a bottom plan view of the drill rod shown in Figure 6.

Figure 8 is a sectional elevation, partly in section, illustrating meansfor preventing relative rotation between the drill rod and bit.

Referring to Figures 1 and 2, at 10 is shown the end of a drill rodwhich may be of any desired form or shape. The drill rod 10 at its end11 is provided with a socket 12, which may be formed in the end of thedrill rod 10 by any suitable means such as forging, drilling, cutting,etc. Bit 13 is provided with a shank 14 which conforms more or lessclosely to the contour of the socket 12. In Figures 1 and 2 the shank 14and the socket 12 are shown tapered and with a circular cross section.The arrangement is such that when the shank 14 is firmly pressed orforced into the socket 12 so as to hold the bit 13 on to the drill rod10, the end 11 of drill rod 10 firmly engages the bit 13 for instance byseating in an annular groove 15 on bit 13.

It will thus be seen that the shank 14 and socket 12 function to holdthe bit and drill rod together and that the end 11 of drill rod 10, andthe upper part of the body of bit 13, for instance groove 15, functionto transmit all of the forces from the drill rod to the bit.

It will be noticed that the forces from the drill rod are transmitted tothe bit over an annular area bounded by the inner and outercircumferences of the end of the drill rod. This annular area is shownas being continuous, but may be made discontinuous without'departingfrom the spirit of the invention.

By having the area over which the forces are transmitted from the drillrod to the bit bounded by the inner and outer circumferences of thedrill rod, the forces are transmitted over a larger area and are alsovery evenly distributed over the cutting surface of the bit.

To prevent any tendency of the end of the drill rod 10 to spread Iprovide a circumferentially continuous or discontinuous ridge 16, whichcontacts and fits tightly against the outer circumferential surface ofend 11 when the bit 13 is in place on the drill rod 10.

In practice I find it very advantageous to harden the end of drill rod10 and to treat the shank 14 so that it will be soft. The hardening ofthe end of the drill rod not only increases its resistance to spreadingand otherwise deforming, but also increases its resistance to abrasion.The soft shank 14, even though slightly oversize, will conform readilyto the contour of the hardened socket 12. The shank 14 will conform toany inequalities of the inner surface of the socket 12 and will thuspermit the end 11 of drill rod 10 to contact the upper part of the bodyof the bit 13, as by fitting snugly in groove 15.

It is, of course, understood that the working surface of the bit 13 hasbeen given the proper or desired heat treatment for hardening purposes.This treatment might include the surface contacted by the end 11 ofdrill rod 10, if desired.

To increase the oversize tolerance for the shanks and to assist inpreventing relative rotational movement between the bit and drill rod, Imay provide longitudinal straight or curved grooves 17 in the wall ofsocket 12.

The grooves 17 will take care of a large degree of oversize in the shank14, the excess material flowing, so to speak, into the grooves, and willgrip the shank to prevent relative rotational movement. The grooves maybe of any width and number.

In operation it is merely necessary to insert the shank 14 into thesocket 12 in the end 11 of the drill rod 10, and to force it home with awooden block, lead hammer or othersuitable device. When the parts areproperly made the end 11 of drill rod 10 will contact the upper part ofthe body of bit 13. To remove the bit it is merely necessary to strikeit with a suitable tool such as a lead hammer. A new bit may then bequickly inserted, and the drilling continued without more than a fewmoments delay.

The form shown in Figures 3 and 4 is in all respects identical with thatshown in Figures 1 and 2 except that the socket 112 is given a taper ofoval cross section instead of circular. The shank on the bit would havea similar taper. The cross section of the taper may have any othergeometrical shape. The socket may be provided with grooves if desired.

In the form shown in Figure 5 the rod 210 has a socket 212 formedinwardly with the customary taper, but has a straight portion at itsouter end, as shown at 18. The shank 214 on bit 213 is likewise providedwith a straight portion shown at 19 so as to conform with the contour ofthe socket 212. The tapered, as well as the straight portion may have across section of any other geometrical shape, and the socket may beprovided with grooves, if desired.

In Figures 6 and 7 I have shown a modification in which the shank 314 isformed on the drill rod 310 and the socket 312 is formed in the bit 313.The end 311 of drill rod 310 is given a geometrical shape other thancircular, such as square, and fits into a recess in bit 313 of likecontour, shown at 315, so that the upper surface of the recess will becontacted by the lower surface of.the end 311 when the shank 314 isforced into the socket 312. In this instance the shank may be hardenedand the wall of the socket left or made soft, if desired so as toaccommodate fitting.

In Figure 8 I have shown a further form of the invention in which thesocket 412, shank 414 the drill rod and bit is thus prevented. Any.

other means might be substituted for the projection 20 such asroughening or knurling the end of the rod 410.

While I have particularly described several shapes of shanks and socketsit is obvious that other forms might be substituted provided thenecessary wedging action and elasticity is secured between the shank andthe socket to hold the bit in place and to permit direct contact betweenthe end of the drill rod and the body of the bit so that the forces ofdrilling may be transmitted directly from the drill rod to the body ofthe bit without resort to the socket and the shank. For instance, manyof the usual forms of shanks on cutters might be suitable and the usualdevices thereon to prevent rotation might be substituted for those shownin the drawing without departing from the spirit of the invention.

The structure of my invention is very simple, durable, and highlypracticable. The bits, for instance, might be forged in one operationand hardened in another, thus lending themselves to quantity productionat a very low cost. If the bits are formed with relatively soft shanks,the inequalities in forging will be taken care of by the shankconforming to the contourof the socket in the end of the drill rod. Thisis particularly true if the socket is provided with grooves of anycharacter such as those shown at 1'7. Spreading of the end of the drillrod is effectually lessened by the continuous hardened circumferentialannular wall forming the end oi Itisestimatedthatthebltscanbemadeinquantity so cheaply that they may be discarded much. the same as safetyrazor blades after becoming dull.

Having described my invention it is obvious that many modifications maybe made in the same within the scope of the claims without departingfrom the spirit thereof.

I claim:

I. A device of the kind described comprising a drill rod, a bit, asocketin the end of said drill rod having inwardly convergingcircumterentialiy continuous side walls, longitudinal grooves in saidsocket, a shank on said bit adapted to be forced tightly into saidsocket and to be firmly secured in said socket solely by virtue ot theresulting i'sht fit, said grooves asinthe fltotsaidshankandsocket, saidoisaiddrillrodandsaid biti'ormedsoas beflrmlylncontactwitheachotherwhenshank is in position in said socket. so that the drilling iorces will betransmitted directly from the end 01' said drill rod to said bit, and

iorholingsaiddrlllrodandbittosethenand to prevent relative rotationthereoi, the socket oi said drill being of relatively harder materialthan the shank of said bit.

2. Atwomemberdeviceoithekmddescribedcomprisingadrillrodandabitasocketintheendotoneoisaidmembershavinginwardly converging circumierentiallycontinuous side walls of relatively hard material. longitudinalmitteddirectlyfromtheendofsaiddrillsocket,sothatthedrillingi'orceswillbetransmitted directly from the endoi said drill rod to said bit, and said shank and socket functionprimarily for holding said drill rod and bit together.

3. A two member device 0! the kind described comprising a drill rod anda bit, a socket in the end 01 one of said members having inwardlyconverging circumierentially continuous side walls of relatively hardmaterial, longitudinal grooves in said socket, a shank at relativelysoit material on the other of said members adaptedtobeioroedtishtlyintosaidsocketandtobeflrmlysecuredinsaidsocketbyvirtueoitheresultins tight at, one of saidtisht fitting parts beingrelativelyhardandtheotherbeinsrelatively soft,said drill rod and said bit formed soastobeflrmlyincontactwitheachotherwhensaidshankisinpositioninsaidsockehsothat the drilling force will betransmitted directly of said drill rod to said bit. and

hcldins said drill rod and bit tcsether.

4.Adeviceoithekinddescrlbedcomprisingadrillrod,a'bit.asocketintheendotsaid drill rod having inwardlyconveraingcircmnin said socket by virtue of the resulting'ilt,saidgroovesinthefltoisaid.-andsocket,saidendoisaiddrillrodandsaidbitiormedsoastobeiirmlyincontact with other whensakishankkinpositicninsocketsothatthedrlllingiorceswillbe thereof.

GHARLIS LANG.

